U.S. Pat. No. 5,106,910 describes a mixture of polyvinylidene fluoride, nylon 11 and a compatible adhesive to secure the coating to the substrate. The preferred composition is polyvinylidene fluoride, nylon and a nylon terpolymer/caprolactam adhesive. The coating is preferably applied by plasma spray.
U.S. Pat. No. 3,340,222 suggests inter alia that amide group containing polymers may be used in connection with fluoropolymers to aid in film formation and ultimate coating performance. At a maximum 50% of the combination is to be the amide group containing polymer and on closer examination of the text it its clear that the amide containing polymers referred to are acrylamide polymers not polyamide polymers.
U.S. Pat. No. 3,826,794 describes the addition of selected polyamide polymers to polyvinylidene fluoride based polymers for the purpose of improving the impact strength of PVDF polymers. The amount of polyamide is from 30% to 55% by weight and the choice of polyamide is stated to be critical. Polyamide from aminoundecanoic acid, polyamide (nylon) 11 if made from the commonly available aminoundecanoic acid, 10-aminoundecanoic acid, is specifically stated to be incompatible with PVDF polymers along with polyamides from 6-aminocaproic acid.
Suitable polyamides are stated to be those described from branched diamines having carbon chain lengths defined in the patent.
The present invention provides mixtures of PVDF polymers and polyamide 11, or polyamide 12, having less than 45% by weight PVDF polymers which are fusible powders suitable for providing pigmented or unpigmented coatings on substrates, particularly metal substrates and which are also capable of being formed by common techniques, such as by injection molding or extrusion, into two or three dimensional objects having superior surface properties to corresponding polyamides not containing the PVDF polymers. The compositions of the instant inventions are free of the compatible adhesive of U.S. Pat. No. 5,106,910.